The present invention is concerned with application programs running on a client device that display information obtained from a wide area network to a user through a user interface.
Users of computer systems use their computers to perform a variety of tasks, such as word processing, spread sheets, games, and email. Each of these tasks typically involves activating a user application program that interacts with the user to perform the task. An application is a software program that carries out a task, i.e. a database manager, a spreadsheet, a communications package, a graphics program or a word processor. User input is received from the user via user input devices, such as a mouse and keyboard, and information is output to the user by outputting information to the user via a display, such as a monitor.
Each user application typically has its own user interface. In other words, each application accesses data that is typically specific to the application, processes the data, and assembles and formats textual and graphical data for display to the user. The data for each application is typically formatted and structured specifically for the application, so, unless multiple applications are designed to share data, it is often difficult for one application program to access and utilize the data from another application program. Furthermore, the task of assembling and formatting data for output to the user can be complex. Each user application typically uses the interface drivers provided by the operating system of the computer system to output information to the display of the computer system. However, the user interface software for each program is often substantially custom for that program and can represent a significant amount of the code for each application.
Another type of user application is a browser application, which provides users of computer systems access to a vast amount of information through their network connections to the Internet. The Internet is a wide area network that interconnects computer networks around the world and provides a user client device connected to the Internet with access to a broad array of resources connected to the Internet, i.e. access to servers that are also connected to the Internet. In order for information to be accessible to a wide number of client devices and servers, a body of software, a set of protocols and a set of defined conventions are generally needed that permit intercommunication. The World Wide Web is one example of such a body of software, set of protocols and set of defined conventions.
The World-Wide-Web and similar private architectures, such as internal corporate LANs, provide a “web” of interconnected document entities. On the World-Wide-Web, these document entities are located on various sites on the global Internet. The World-Wide-Web is also described in “The World-Wide Web,” by T. Berners-Lee, R. Cailliau, A. Luotonen, H. F. Nielsen, and A. Secret, Communications of the ACM, 37 (8), pp. 76-82, August 1994, and in “World Wide Web: The Information Universe,” by Berners-Lee, T., et al., in Electronic Networking: Research, Applications and Policy, Vol. 1, No. 2, Meckler, Westport, Conn., Spring 1992. On the Internet, the World-Wide-Web is a collection of documents (i.e., content), client software (i.e., browsers) and server software (i.e., servers) which cooperate to present and receive information from users. The World-Wide-Web is also used to connect users through the content to a variety of databases and services from which information may be obtained.
The World-Wide-Web is based on a conventional client-server model. Content is held in documents accessible to servers. Clients can request, through an interconnect system, documents which are then served to the clients through the interconnect system. The client software is responsible for interpreting the contents of the document served, if necessary.
Among the types of document entities in a “web” are documents and scripts. Documents in the World-Wide-Web may contain text, images, video, sound or other information sought to be presented, in undetermined formats known to browsers or extensions used with browsers. The presentation obtained or other actions performed when a browser requests a document from a server is usually determined by text contained in a document which is written in Hypertext Markup Language (HTML). HTML is described in HyperText Markup Language Specification—2.0, by T. Berners-Lee and D. Connolly, RFC 1866, proposed standard, November 1995, and in “World Wide Web & HTML,” by Douglas C. McArthur, in Dr. Dobbs Journal, December 1994, pp. 18-20, 22, 24, 26 and 86. HTML documents stored as such are generally static, that is, the contents do not change over time except when the document is manually modified. Scripts are programs that can generate HTML documents when executed.
HTML is one of a family of computer languages referred to as mark-up languages. Mark-up languages are computer languages which describe how to display, print, etc., a text document in a device-independent way. The description takes the form of textual tags indicating a format to be applied or other action to be taken relative to document text. The tags are usually unique character strings having defined meanings in the mark-up language. Tags are described in greater detail, below.
HTML is used in the World-Wide-Web because it is designed for writing hypertext documents. The formal definition is that HTML documents are Standard Generalized Markup Language (SGML) documents that conform to a particular Document Type Definition (DTD). An HTML document includes a hierarchical set of markup elements, where most elements have start tag, followed by content, followed by an end tag. The content is a combination of text and nested markup elements. Tags are enclosed in angle brackets (‘<’ and ‘>’) and indicate how the document is structured and how to display the document, as well as destinations and labels for hypertext links. There are tags for markup elements such as titles, headers, text attributes such as bold and italic, lists, paragraph boundaries, links to other documents or other parts of the same document, in-line graphic images, and many other features.
A site, i.e. an organization having a computer connected to a network, that wishes to make documents available to network users is called a “Web site” and must run a “Web server” program to provide access to the documents. A Web server program is a computer program that allows a computer on the network to make documents available to the rest of the World-Wide-Web or a private web. The documents are often hypertext documents in the HTML language, but may be other types of document entities as well, as well as images, audio and video information.
The information that is managed by the Web server includes hypertext documents that are stored on the server or are dynamically generated by scripts on the Web server. Several Web server software packages exist, such as the Conseil Europeen pour la Recherche Nucleaire (CERN, the European Laboratory for Particle Physics) server or the National Center for Supercomputing Applications (NCSA) server. Web servers have been implemented for several different platforms, including the Sun Sparc 11 workstation running the Unix operating system, and personal computers with the Intel Pentium processor running the Microsoft.RTM. MS-DOS operating system and the Microsoft.RTM. Windows.TM. operating environment.
A user typically accesses the resources of the World Wide Web through the use of a browser application program. The browser program allows the user to retrieve and display documents from Web servers. Some of the popular Web browser programs are: the Navigator browser from NetScape Communications Corp., of Mountain View, Calif.; the Mosaic browser from the National Center for Supercomputing Applications (NCSA); the WinWeb browser, from Microelectronics and Computer Technology Corp. of Austin, Tex.; and the Internet Explorer, from Microsoft Corporation of Redmond, Wash. Browsers exist for many platforms, including personal computers with the Intel Pentium processor running the Microsoft.RTM. MS-DOS operating system and the Microsoft.RTM. Windows.TM. environment, and Apple Macintosh personal computers.
A browser typically executes on a client device connected to Internet. The Web server and the Web browser communicate using the Hypertext Transfer Protocol (HTTP) message protocol and the underlying transmission control protocol/internet protocol (TCP/IP) data transport protocol of the Internet. HTTP is described in Hypertext Transfer Protocol—HTTP/1.0, by T. Berners-Lee, R. T. Fielding, H. Frystyk Nielsen, Internet Draft Document, Oct. 14, 1995, and is currently in the standardization process. At this writing, the latest version is found in RFC 2068 which is a draft definition of HTTP/1.1. In HTTP, the Web browser establishes a connection to a Web server and sends an HTTP request message to the server.
Request messages in HTTP contain a “method name” indicating the type of action to be performed by the server, a URL indicating a target object (either document or script) on the Web server, and other control information. Response messages contain a status line, server information, and possible data content. The Multipurpose Internet Mail Extensions (MIME) are a standardized way for describing the content of messages that are passed over a network. HTTP request and response messages use MIME header lines to indicate the format of the message. MIME is described in more detail in MIME (Multipurpose Internet Mail Extensions): Mechanisms for Specifying and Describing the Format of Internet Message Bodies, Internet RFC 1341, June 1992.
The user enters a resource identifier value that identifies a desired web resource through a command input line of the user interface of the browser. The resource identifier value is typically a Uniform Resource Identifier (URI) or a Uniform Resource Locator (URL) that is resolved into an address for a server device having the desired object. See Request for Comment (RFC) 1630 available through the Internet Engineering Task Force at URL www.ietf.org.
When a URL value has been input to the browser, the browser transmits a command containing the URL value. The command is typically formatted according to a Hypertext Transfer Protocol (HTTP) that provides a convention for commands and replies over the web. The URL value in the command is typically resolved to an address for a server connected to the web and to a resource on the server, such as a document. See RFC 1945. The server that receives the command will typically respond with an HTTP reply message containing information. This information is typically in the form of a document that uses the Hypertext Mark-up Language (HTML).
In response to an HTTP request message, the server performs any requested action and returns an HTTP response message containing an HTML document resulting from the requested action, or an error message. The returned HTML document may simply be a file stored on the Web server, or it may be created dynamically using a script called in response to the HTTP request message. For instance, to retrieve a document, a Web browser residing in a client device sends an HTTP request message to the indicated Web server, requesting a document by its URL. The Web server then retrieves the document and returns it in an HTTP response message to the Web browser. If the document has hypertext links, then the user may again select a link to request that a new document be retrieved and displayed.
The server constructs the HTML reply message by retrieving an HTML document corresponding to the URL value. The HTML document typically includes markup data that encodes a description of the HTML document's graphical layout and logical structure and includes a set of tags that identify data entities that are to be retrieved and inserted into the HTML document as indicated by the tag. The server typically obtains the data for the HTML document by performing a Server Side Include (SSI) request for each tag value. The SSI request is sent to a database manager that may be internal to the server itself or may be connected to the server via a backend network. The database manager uses the tag value to search aid retrieve the data object corresponding to the tag value. The data object is returned to the server for incorporation into the HTML document. When the server has completed the population of the HTML document with the data entities for each tag of the HTML document, the server will transmit the HTML document in the reply to the client device.
As another example, a user may fill in a form requesting a database search, the Web browser will send an HTTP request message to the Web server including the name of the database to be searched and the search parameters and the URL of the search script. The Web server calls a program or script, passing in the search parameters. The program examines the parameters and attempts to answer the query, perhaps by sending a query to a database interface. When the program receives the results of the query, it constructs an HTML document that is returned to the Web server, which then sends it to the Web browser in an HTTP response message.
When the client device receives the response from the server containing the HTML document, the browser will process the document according to the HTML standard and display the resulting page to the user via the display of the user's computer system.
U.S. Pat. Nos. 5,973,696; 6,006,242; 5,983,228; and 5,737,739 provide additional examples of web architectures and applications and are herein incorporated by reference.
FIG. 1 is a functional block diagram illustrating an example of an architecture 10 involving a client device 20, e.g. a user's computer system, and a server device 60 that can communicate via a network, such as the Internet. Client device 20 includes a keyboard 24 and a mouse 26 as user input devices and a display 28 for user output. Client 20 has a communications port, such as a network interface card, through which it is connected to a local area network (LAN) 30 via communication link 22. LAN 30 is connected to a public Internet Protocol (IP) network 50, i.e. a wide area network, that provides access to a broad range of network resources including those of server 60, which is connected to public IP network 50 via communication link 62. Client device 20 is controlled by a user through a combination of command inputs via mouse 26 in concert with keyboard 24 to execute application programs in client device 20 that display output to the user via display 28.
FIG. 2 is a functional block diagram illustrating an example of another architecture 15 involving a client device 20, e.g. a user's computer system, and a server device 60 that can communicate via a network, such as the Internet. In architecture 15, client device 20 includes a communications device, such as a modem, capable of communicating through public switched telephone network (PSTN) 35 to a network access server (NAS) 40. NAS 40 is connected to IP network 50 and enables client device 20 to communicate with server 60.
FIG. 3 is a simplified functional block diagram illustrating an embodiment of an architecture 100 for a central processing unit (CPU) for client device 20. The CPU includes a processor 110 connected to a system bus 120. Processor 110 accesses several subsystems via bus 120 including a memory subsystem 130 for storage of data and code. A network interface subsystem 140 is connected to bus 120 and is used to communicate with the network via connection 22. The network interface may, for example, be a network interface card or a modem device that communicates with a network access server connected to public IP network 50.
The CPU outputs information to the user via a display interface 150 connected to bus 120 that sends video information to display monitor 28. The CPU receives user input via user interface 160 that receives user input via keyboard 24 and mouse 26 and forwards the user input to processor 110 via bus 120.
FIG. 4 is a simplified software architecture diagram illustrating an embodiment of a software architecture 200 for a typical client device 20. At the center of architecture 200 is an operating system (OS) 210 that controls access to the resources of the client device, including memory, display and communications, and activation of application programs 260 and 270. Output to display monitor 28 of client 20 is accomplished using the display driver primitives 230 provided through OS 210. User input from keyboard 24 and mouse 26 is detected by user interface drivers 240, which receive, interpret, and forward the user input signals to OS 210 for further action. Communications with the network connection 22 are handled through communications drivers 250.
A user of client device 20 selects one of user application programs 260 and 270 through a combination of user inputs. For example, the user may double click an icon displayed on monitor 28 with mouse 26 to activate user application 260. OS 210, upon receiving the user's selection, spawns a process for the selected application.
The application 260 will typically operate with a data store 262, which is a portion of memory subsystem 130 allocated to the application. For example, application 260 may be a word processor that retrieves a document from long term storage, such as a disk drive that is part of memory subsystem 130, and buffers the document in a random access memory (RAM) that is also part of the memory subsystem. The data in data store 262 is typically formatted for use only by the application. For another application to share data, it must be designed to read the data. For example, a word processor application may be configured so that it can read data from a spreadsheet application or import a graphic created by a graphics application.
As an application processes data, it also formats the data for display to the user and outputs the display data using display drivers 230. Above the display driver level, each application essentially includes its own graphical display capability. When, for example, application 260 is a word processor, it formats the ASCII codes and control characters from a document along with the menu and control bars for display via monitor 28 and outputs the formatted document to the user using display drivers 230. When, for example, application 270 is a browser application, it communicates through communication drivers 250 to send a HTTP request containing a URL over the network and receive an HTML document in response. The browser application then renders the graphics and text of the HTML document into a page and outputs the page to the display monitor 28 using display drivers 230.
The separate graphics capability required for each of the applications residing on a client device can become a significant limitation in a client device having limited resources. Likewise, the inability to efficiently share data across multiple applications can also pose a problem. Therefore, the need remains for a software architecture that efficiently uses the resources available in a client device.